A conventional door lock as shown in FIG. 1 may include a latch L for locking the door D on a door frame F which latch L is generally formed with a sloping surface for a smooth closing operation of the door. However, when such a door lock is used in a door provided with an automatic door closer either hydraulic operated or spring loaded may not be completely closed because the closing force acted by the automatic door closer may be not enough to retract the latch L bearing against the strong spring force acting on the latch L, thereby unable to completely close the door by engaging the latch L with the socket S as shown in dotted line in FIG. 1.
As shown in FIG. 1A, a recently developed door lock having a retractor RT sandwiched between a pair of latches L as shown in the figure is provided to enforce a door closing operation as effected by an automatic door closer, for instance, by overcoming a spring restoring force acting on the latches, which however still requires a closing force equal to the restoring force by the latch spring and does not substantially save the door closing force.
The present inventor has found the drawback of the conventional door lock and invented the present door lock with lightly-closing force.